Turbine blades of a core jet engine are exposed to temperatures beyond the ability of available materials to withstand without some means for cooling such blades. One method of cooling involves passing cooling air through passages in the interior of the turbine blades. Problems occur in transferring the air from the stationary pressure source to the rapidly rotating turbine blades. In the prior art, a system of labyrinth seals, typically consisting of three seals, has been used to provide the pressure gradient needed to move the air into the turbine blades. One typical way of accomplishing this sealing is disclosed in U.S. Pat. No. 3,989,410.
Such rotating seals operating in differential pressure environments produce axial forces on the rotating member. Careful balancing of seal effective areas has been required in order to counterbalance such axial forces.
Rotating seals are expensive components, subject to wear, and require substantial labor for installation. The elimination of one or more of such seals without destroying the ability to move cooling air on board the rotating turbine blades would be desirable.